The present invention relates to a device for controlling a charging system including a generator driven by the internal combustion engine of a vehicle.
Conventional devices for controlling vehicle charging systems are constructed such that the voltage with which a vehicle-carried storage battery is charged is generally controlled to a preset level by a voltage regulator coupled to a generator driven by the internal combustion engine. The voltage regulator may have a temperature compensation circuit for compensating temperature-dependent variations in the charging characteristics of the storage battery. In many instances, the preset voltage level is temperature-compensated with a negative temperature gradient with respect to variations in ambient temperature around the voltage regulator, thereby effecting relative correction of temperature dependent charging characteristics of the storage battery.
The storage battery and the voltage regulator have widely different thermal capacities and are located at different positions. This tends to impair the correlation between their temperature changes, making it difficult to control the output voltage of the generator so as to agree with the optimum charging voltage of the storage battery. Furthermore, since the generator is driven by an internal combustion engine, it is difficult to change, by way of an external approach, the setting for the storage battery voltage in order to reduce the load on the internal combustion engine when the vehicle is accelerated, or decelerated. The charging characteristics of the storage battery are also variable due to changes in its internal resistance during use. Accordingly, complete compensation is not possible based on temperature characteristics that have been fixedly set in advance. It would be highly difficult to perform optimum control of the charging system in a manner so as to meet the characteristics of various types of vehicles and the running patterns thereof.